“Childhood Social Class and Cognitive Aging in the Swedish Adoption/Twin Study of Aging”, 2017 ():
In this report we analyzed genetically informative data to investigate within-person change and between-person differences in late-life cognitive abilities as a function of childhood social class. We used data from 9 testing occasions spanning 28 y in the Swedish Adoption/Twin Study of Aging and parental social class based on the Swedish socioeconomic index. Cognitive ability included a general factor and the 4 domains of verbal, fluid, memory, and perceptual speed.
Latent growth curve models of the longitudinal data tested whether level and change in cognitive performance differed as a function of childhood social class. Between-within twin-pair analyses were performed on twins reared apart to assess familial confounding. Childhood social class was statistically-significantly associated with mean-level cognitive performance at age 65 y, but not with rate of cognitive change. The association decreased in magnitude but remained statistically-significant after adjustments for level of education and the degree to which the rearing family was supportive toward education.
A between-pair effect of childhood social class was statistically-significant in all cognitive domains, whereas within-pair estimates were attenuated, indicating genetic confounding. Thus, childhood social class is important for cognitive performance in adulthood on a population level, but the association is largely attributable to genetic influences.